The present invention relates to a device for transferring a pressure medium from a stationary outer component into a rotatably driven inner component positioned within the stationary outer component, whereby the components are provided with coordinated pressure medium channels.
From German Offenlegungsschrift 35 37 686 a device of the aforementioned kind for feeding a pressure medium to a hydraulically operated clamping cylinder is known. The outer component in this device is rotatably supported with little play on the inner component so that between the two components an axially extending sealing gap is formed. In this area the pressure medium channels provided within both components are arranged. Furthermore, the two components are directly supported on one another by roller bearings.
This constructively simple pressure medium transferring device has been successful in practice. However, the height of the sealing gap is determined by the two roller bearings. Since the small radial distance must be maintained even under varying operational conditions, it is required to use extremely precisely manufactured roller bearings. The costs for such roller bearings are considerable, but it is still unavoidable that especially at high rpms changes of the sealing gap do occur due to uneven temperature distribution and that the components in the area of the sealing gap may be damaged. Furthermore, due to high bearing friction, caused by the growing sealing gap and resulting in a greater amount of pressure medium flowing through the roller bearing, it is also possible that considerable power losses will occur.
It is therefore an object of the present invention to provide a device of the aforementioned kind for transferring a pressure medium in which the two components are neither directly supported on one another nor supported via roller bearings so that no axially extending sealing gap is present. However, the device should provide a reliable pressure medium transfer even under various operational conditions. Positional changes of the inner and/or the outer components, caused by heat load or other external influences, should be compensated automatically without affecting the transfer of pressure medium or the operation of the device. It is also desired that positional inaccuracies should have no unfavorable effects. The constructive expenditure with which the aforementioned advantages are to be achieved should be minimal; furthermore, no expensive machine parts such as roller bearings should be required so that an economic manufacture and a universal application of the device are ensured.